BackgroundThe interface between primary care and specialist medical services is an important domain for health services research and policy. Of particular concern is optimising specialist services and the organisation of the specialist workforce to meet the needs and demands for specialist care, particularly those generated by referral from primary care. However, differences in the disease classification and reporting of the work of primary and specialist surgical sectors hamper such research. This paper describes the development of a bridging classification for use in the study of potential surgical problems in primary care settings, and for classifying referrals to surgical specialties.

MethodsA three stage process was undertaken, which involved: 1 defining the categories of surgical disorders from a specialist perspective that were relevant to the specialist-primary care interface; 2 classifying the -terms- in the International Classification of Primary Care Version 2-Plus ICPC-2 Plus to the surgical categories; and 3 using referral data from 303,000 patient encounters in the BEACH study of general practice activity in Australia to define a core set of surgical conditions. Inclusion of terms was based on the probability of specialist referral of patients with such problems, and specialists- perception that they constitute part of normal surgical practice.

ResultsA four-level hierarchy was developed, containing 8, 27 and 79 categories in the first, second and third levels, respectively. These categories classified 2050 ICPC-2 Plus terms that constituted the fourth level, and which covered the spectrum of problems that were managed in primary care and referred to surgical specialists.

ConclusionOur method of classifying terms from a primary care classification system to categories delineated by specialists should be applicable to research addressing the interface between primary and specialist care. By describing the process and putting the bridging classification system in the public domain, we invite comment and application in other settings where similar problems might be faced.

Electronic supplementary materialThe online version of this article doi:10.1186-1472-6963-4-8 contains supplementary material, which is available to authorized users.